Researchers Develop Anthrax Tracking Method

University of Maryland researchers have developed a technique to help the FBI track the origins of deadly anthrax spores.

The FBI asked Maryland professor Catherine Fenselau to turn her mass spectrometry lab to the forensic task of sleuthing how bacillus spores, such as anthrax, are prepared.

"There are several common types of chemicals that are used to grow anthrax spores," said Fenselau. "One is agar, and another is a blood-based medium containing heme. People tend to develop and use their own recipe to grow the spores.

"By analyzing for traces of these media, we can say a lot about how the spores were grown. That information can help investigators connect the growth with a certain recipe."

Molecules of organic compounds have specific weights. Mass spectrometry can determine what even a single molecule is based on its unique weight. Mass spectrometry analysis has been accepted as evidence in court cases for about 35 years.

"It's very sensitive and very specific," said Jeff Whiteaker, the post-doctoral researcher who developed the process for detecting the heme medium. "The mass spectrometry-based method is more specific for the heme molecule compared to the traditional methods. Even if we encounter compounds that have the same weight, we can confirm which molecule it is by the way it breaks up in the mass spectrometer."

"Our theory was that if you look at what is stuck to the outside of a spore, you can find out how it became a spore." Fenselau said. "Even when you try to clean up the spores, there are still scraps of stuff on the surface."

The Maryland team worked with five of the most frequently used recipes for blood agar to develop a method to detect and identify heme in any medium. "These bacteria grow on anything that has lots of nutrients available, which the heme medium does," Whiteaker explained. "Microbiologists like to use blood agar to grow bacteria like anthrax, because it mimics conditions in the body."

The Maryland researchers worked with non-toxic bacillus spores, "first cousins that have a similar genome to anthrax, but don't have the capability to synthesize the killer toxins," said Fenselau.

The Maryland researchers worked on the analysis from August, 2002 to February, 2003, producing a method where, said Whiteaker, "the heme medium jumps out."

The heme analysis was developed in collaboration with scientists at the FBI Academy. The team presented its results at an international conference in Montreal in June and expects to publish the technique in a scientific journal soon.

The University of Maryland's mass spectrometry laboratory is one of the most sophisticated in the Washington-Baltimore region. Other research in the lab includes studies of how drug resistance develops in breast cancer patients and development of methods for rapid characterization of airborne microorganisms.

Quelle: University of Maryland